Novel HPLC Analysis of Hydrocortisone in Conventional and Controlled-Release Pharmaceutical Preparations

A Pharmacokinetic Evaluation of a Pectin-Based Oral Multiparticulate Matrix Carrier of Carbamazepine

Background

Carbamazepine is a drug used in the treatment of neurological disorders such as epilepsy. However, due to its erratic absorption, oral bioavailability is often poor. There is, therefore, the need to develop alternative formulations for carbamazepine with better pharmacokinetic characteristics.

Aim

The aim of this study was to formulate an oral modified-release multiparticulate matrix of carbamazepine from cocoa pod husk (CPH) pectin and evaluate the pharmacokinetic profile of this formulation using in vitro and in vivo models.

Methods

CPH pectin was extracted from cocoa pod husks with hot aqueous and citric acid solutions. Oral multiparticulate carbamazepine matrices were formulated from CPH pectin cross-linked with calcium. The formulation was evaluated for carbamazepine content and release profile in vitro. For in vivo pharmacokinetic profile estimation, rats were put into 4 groups of 5 animals each to receive carbamazepine multiparticulate matrix formulations A and B, carbamazepine powder, and Tegretol CR^®. Animals in each group received 200 mg/kg of each drug via the oral route. Maximum plasma concentration (C_max), area under the concentration-time curve (AUC), elimination rate constant (K_e), and terminal half-life (t_1/2) of the formulations were estimated by noncompartmental analysis.

Results

The pectin extraction from fresh cocoa pod husks using hot aqueous and citric acid solutions gave pectin yields of 9.63% and 11.54%, respectively. The drug content of carbamazepine in CPH pectin formulations A and B was 95% and 96%, respectively. There was controlled and sustained release of carbamazepine for both formulations A and B in vitro. AUC_0⟶36 (176.20 ± 7.97 µg.h/mL), C_max (8.45 ± 0.71 μg/mL), T_max (12 ± 1.28 h), and t_1/2 (13.75 ± 3.28 h) of formulation A showed a moderately enhanced and comparable pharmacokinetic profile to Tegretol CR^® (AUC_0⟶36: 155 ± 7.15 µg.h/mL, C_max: 8.24 ± 0.45 μg/mL, T_max: 8.0 ± 2.23 h, and t_1/2: 13.51 ± 2.87 h).

Conclusion

Findings from the study suggest that formulations of CPH pectin had the potential to control and maintain therapeutic concentrations of carbamazepine in circulation over a period of time in the rat model.

Potential of Cocoa Pod Husk Pectin-Based Modified Release Capsules as a Carrier for Chronodelivery of Hydrocortisone in Sprague-Dawley Rats

The potential of cocoa pod husk (CPH) pectin-based modified release (MR) capsules as a carrier for chronodelivery of hydrocortisone in Sprague-Dawley rats was assessed. Extemporaneously formulated CPH pectin-based hydrocortisone (10 mg) capsules crosslinked with calcium chloride (Formulation A) or zinc (Formulation B) and a commercial immediate release hydrocortisone formulation were administered orally to Sprague-Dawley rats and the pharmacokinetic parameters were evaluated using noncompartmental analysis. Formulation A had a 2 h lag phase followed by an increase in serum drug concentration in the treated rats. Peak concentrations (C_max) of 21.799 ± 1.993 ng/ml and 20.844 ± 2.661 ng/ml were achieved after 6 ± 0.23 h and 6 ± 0.35 h (T_max), respectively, for capsules A and B. The immediate release formulation had a peak concentration of 15.322 ± 0.313 ng/ml within 1 ± 0.2 h. The relative bioavailability of the CPH pectin-based capsules A and B was 213% and 274%, respectively. Formulations A and B had half-lives more than three times that of the immediate release formulation. The MR capsules exhibited a higher exposure, greater bioavailability, and versatility in release of cortisol than the commercial immediate release formulation. Additionally, the MR capsules exhibited an extended drug release with overnight cortisol rise and early morning cortisol peak and hold promise in the management of adrenal insufficiency.

In Vitro Evaluation of Cocoa Pod Husk Pectin as a Carrier for Chronodelivery of Hydrocortisone Intended for Adrenal Insufficiency

This study evaluated the in vitro potential of cocoa pod husk (CPH) pectin as a carrier for chronodelivery of hydrocortisone intended for adrenal insufficiency. FTIR studies found no drug-CPH pectin interactions, and chemometric analysis showed that pure hydrocortisone bears closer similarity to hydrocortisone in hot water soluble pectin (HWSP) than hydrocortisone in citric acid soluble pectin (CASP). CPH pectin-based hydrocortisone matrix tablets (~300 mg) were prepared by direct compression and wet granulation techniques, and the tablet cores were film-coated with a 15% HPMC formulation for timed release, followed by a 12.5% Eudragit® S100 formulation for acid resistance. In vitro drug release studies of the uncoated and coated matrix tablets in simulated gastrointestinal conditions showed that wet granulation tablets exhibit greater retardation of drug release in aqueous medium than directly compressed tablets. CASP showed greater suppression of drug release in aqueous medium than HWSP. Wet granulation HWSP-based matrix tablets coated to a final coat weight gain of ~25% w/w were optimized for chronodelivery of hydrocortisone in the colon. The optimized tablets exhibited a lag phase of ~6 h followed by accelerated drug release in the colonic region and have potential to control night time cortisol levels in patients with adrenal insufficiency.